Here's how previous editions of Soulcalibur have done in the UK (LTD):
Soulcalibur (SDC, 1999) < 100k
Soulcalibur II (PS2, 2003) 200k - 300k
Soulcalibur II (NGC, 2003) < 100k
Soulcalibur II (XBX, 2003) < 100k
Soulcalibur III (PS2, 2005) < 100k
Not a very big series in the UK, but SC II shows that it does have some potential.